I've never done one on a E70 but It should be pretty straightforward...

- Drain the fuel.
- Disconnect any fuel lines/hoses and connectors for the sending unit/gauge) first.
- Check the access panels in the floor of the trunk and underneath the car to make sure everything is disconnected.
- Before you drop it remember to take off the fuel filler cap.
- While the tank is out you might want to use Marine Clean to clean out the inside.